Pseudoelasticity in pseudo-binary Fe3(Al1−xGax) single crystals

Abstract

Pseudoelastic behavior of pseudo-binary Fe3(Al1−xGax) single crystals with the D03 structure was examined focusing on the dependence on x and annealing condition. At x = 0.2–0.8, the D03 single phase developed below about 773–873 K. In the D03-ordered crystals compressed with [1¯49] axis at room temperature, reversible motion of 1/4[111] superpartial dislocations dragging the antiphase boundaries (APB) contributed to the strain recovery, similar to Fe3Al and Fe3Ga binary crystals. In the pseudo-binary crystals after D03 ordering treatment by slow cooling, 1/4[111] superpartials trailing the nearest-neighbor APB were dominantly observed below x = 0.4 while the paired superpartials moved dragging the next-nearest-neighbor APB at and above x = 0.4. During unloading, both the APBs pulled back the superpartials due to their tension resulting in the pseudoelasticity. The amount of strain recovery varied with x, which was closely related to the dislocation configuration. Annealing in the D03 single-phase region affected the dislocation configuration and the backward stress due to APB, which influenced the pseudoelastic behavior.